Soil Instruments VW range usually includes an NTC 3kΩ Thermistor. This means the temperature measured will be in Ω. To convert this into °C  the Steinhart-Hart equation is used.

If you are using a Soil Instruments thermistor with a datalogger or readout also supplied and manufactured by Soil Instruments the coefficients will already be input into the program and the temperature will already be calculated. 

The Steinhart-Hart equation.

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The below chart is also a useful reference to convert from thermistor resistance to degrees centigrade.



This formula and chart are applicable to all vibrating wire instruments that are supplied with thermistors.